body {
    font-family: Arial, sans-serif;
    height: 100vh;
    margin: 0;

    display: flex;
    justify-content: center;
    align-items: center;

    background: linear-gradient(270deg, #6a11cb, #2575fc, #ff6a00);
    background-size: 600% 600%;
    animation: gradientBG 12s ease infinite;
}

@keyframes gradientBG {
    0% { background-position: 0% 50%; }
    50% { background-position: 100% 50%; }
    100% { background-position: 0% 50%; }
}

.container {
    background: rgba(255, 255, 255, 0.95);
    padding: 30px;
    width: 420px;
    max-width: 90%;

    border-radius: 15px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.2);
    text-align: center;

    transition: 0.3s;
}

.container:hover {
    transform: scale(1.03);
}

h1 {
    margin-bottom: 20px;
}

.input-area {
    display: flex;
    gap: 10px;
}

input {
    flex: 1;
    padding: 12px;
    border: 2px solid #ddd;
    border-radius: 8px;
}

button {
    padding: 12px;
    border: none;
    background: #2575fc;
    color: white;
    border-radius: 8px;
    cursor: pointer;
    transition: 0.3s;
}

button:hover {
    transform: scale(1.1);
}

ul {
    padding: 0;
    margin-top: 15px;
}

li {
    list-style: none;
    background: #f1f1f1;
    margin: 10px 0;
    padding: 12px;
    border-radius: 8px;

    display: flex;
    justify-content: space-between;
    align-items: center;

    opacity: 0;
    transform: translateY(-20px);
    transition: 0.4s;
}

li.show {
    opacity: 1;
    transform: translateY(0);
}

li:hover {
    transform: scale(1.02);
}

.completed {
    text-decoration: line-through;
    color: gray;
    background: #d4edda;
}

li.remove {
    opacity: 0;
    transform: translateX(100px);
}